Stages of Grief

Always found Inside Out to be a perfect example of the stages of grief.

Reilly's Joy is clearly stuck in denial for the first half of the film, grief (sadness) gets picked on by her and she goes on and on about how great it is to be leaving all Reilly's friends behind. Yes, little miss Reilly isn't going to be affected at all by this, Joy is at the controls, lets ignore your suffering.

Of course, Anger is when Joy isn't around to helm the controls anymore and Anger steps up to try and act like Joy. We also see this in Joy, who blames everything that is going on on Sadness. That if Sadness had just let Joy keep Reilly in denial none of these changes to Reilly's subconscious would be happening.

Bargaining, if I go back to Colorado then I can get new memories with my old friends and everything will be the same again. Joy believing that if she could just get this core memory back then all the changes happening in Reilly's subconscious would go back to normal. Goof ball island would come back as would everything else. Change is bad, but perhaps we can undo the change.

Acceptance, we have both Reilly and Joy accepting that change is here to stay and that it can be a good thing.